i have the 4.5" and 6" nils hand auger
i have had the 4.5" for about 4 years now, and it has yet to show any signs of slowing down
got the 6" last march, cuts just as good as the 4.5", and still faster than any other handauger, and most poweraugers.
Also, the blades just do not seem to want to go dull
-however, i talked to the guys(nils importers) in jercho, VT., and they said that if somehow you do dull the blade head, you would have to have a machine shop work on it.
not a worry of mine though, 4 seasons, over 140 trips total so far on the 4.5", and not a problem yet.